<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
<script>
    let promise = new Promise(function executor(resolve,reject){
        let number = Math.random();
        if(number>0.5){
            resolve(number);
        }else{
            reject('太小了');
        }
    });
    console.dir(promise)
</script>
</body>
</html>